Tungurahua (Ecuador): volcano might erupt again soon

The Geophysical Institute warned that a new eruptive phase might be in the making at the volcano, which is one of the world's most active. Geophysical monitoring stations have been recording a significant, steady inflation (swelling) of the volcanic edifice. This is most likely a sign of new magma intruding at shallow depth.
Seismic activity of the volcano has been generally low, with less than two earthquakes per day. Only some small earthquake swarms have been detected recently; such swarms are common in periods of quiescence and are associated with fluid movements within the volcano. Degassing of the volcano has also been at the lower end. However, this apparent calm could be deceiving: it might well be explained by a blockage of the conduit, not the absence of magma ready to erupt.

The volcano has only been quiet since its last eruption in February-March this year, but its phases of calm have never lasted very long. In the last 8 years of activity, Tungurahua has had 15 similar quiet periods characterized by low seismic and degassing activity coupled with an inflationary deformation trend.
In most cases, these quiet periods were followed by small to moderate eruptions, but sometimes also by violent, larger explosions. What makes it difficult for volcanologists to predict the next eruption is that clear precursory signs of new eruptions in the short term (hours to days) have only been detected in 20% of cases; many eruptions started very quickly at the volcano. In any case, based on the current seismic and geophysical observations and the volcano's past behavior, a new eruption in the medium term (weeks to months) is considered very likely.

According to IGEPN, the two most likely scenarios are:
1) a gradual awakening with mild to moderate strombolian activity, lava fountains and associated ash emissions that typically do not exceed 6 km height - examples include the eruptions in April-May 2011 , March 2013, April 2015.
Main hazards near the volcano would be ballistic ejecta (blocks and volcanic bombs) and small pyroclastic flows that could reach a distance of 2.5 km from the crater. Small secondary lahars could be caused by the re-mobilization of eruptive material by rain and could again cut the road Baños-Penipe. This is considered the most likely development in the coming weeks / months.


Or: 2) the second most likely scenario should also be taken into account as possibility: a violent, sudden vent-clearing explosion that could produce tall ash plumes - up to 10 km or more - and dangerous pyroclastic flows that reach the feet of the volcano and beyond. Ballistic ejecta and pyroclastic flows could impact areas in a radius of 5 km or more.

Whether the volcano will erupt in the near future, and if so, which of the described scenarios it will follow is impossible to predict at the moment.